1. Field of the Invention
The present invention relates to a method of handling, for example, moving vertically and otherwise, a relevant member of a crystal pulling apparatus used for pulling a seed crystal from a melt of a polycrystalline material to thereby obtain a single crystal. The present invention also relates to a mechanism for performing the method and a jig used in the method and mechanism.
2. Description of the Related Art
Conventionally, a pulling method (Czochralski method, hereinafter called the "CZ" method) and a floating zone method have been known as methods for obtaining a single crystal from a polycrystalline material such as silicon. In the CZ method, a polycrystalline material is first melted, and a seed crystal is pulled upwardly from the melt of the polycrystalline material. In this method, a shaft or a cable is employed to pull the seed crystal.
FIG. 4 shows an example of a conventional crystal pulling apparatus employing a cable. As shown in FIG. 4, the crystal pulling apparatus 100 includes a chamber 101, a crucible 102 disposed within the chamber 101, a heater 105 disposed around the crucible 102, a crucible holding shaft 107 and a rotating mechanism 108 for rotating the crucible 102, a seed chuck 111 for holding a seed crystal S of silicon, a cable 110 for pulling the seed chuck 111, and a winding mechanism 109 for rotating and winding up the cable 110.
The above-described chamber 101 includes a disk-shaped base plate 101B, a main chamber 101M which accommodates the crucible 102 and the like, a top plate 101T which serves as the ceiling portion of the main chamber 101M and a pull chamber 101P which is connected to the top plate 101T and through which the cable 110 is wound up and a single crystal is pulled.
The crucible 102 is composed of a quartz crucible 103 for accommodating a melt L therein, and a graphite crucible 104 which surrounds the quartz crucible 103. The heater 105 is a tubular member made of graphite, and is disposed so as to surround the crucible 102. The heater 105 has many slits which alternately extend from both axial ends of the heater 105. A heat-insulating cylinder 106 formed of a graphite material is disposed around the outer circumference of the heater 105.
Next, a description will be given of a method for growing a single crystal using the above-described crystal pulling apparatus 100.
First, a highly purified polycrystalline material of silicon is heated to a temperature higher than its melting point (about 1400.degree. C.) so as to be melted. Subsequently, the cable 110 is released out such that the tip of the seed crystal S comes into contact with or is dipped into the surface of the melt L at the substantially central portion thereof. The crucible holding shaft 107 is then rotated in a desired direction, and the cable 110 is wound up while being rotated, so as to pull the seed crystal S. In this manner, the operation for growing a single crystal is started. Subsequently, this operation is continued while the pulling speed and the temperature are properly adjusted, so that a single crystal ingot C having a generally cylindrical shape is obtained.
However, recently, the diameter of a single crystal which is grown by the above-described conventional crystal pulling apparatus has tended to increase. This tendency is accompanied by an increase in the size of a graphite crucible and other relevant graphite members, resulting in an increase in the weight thereof Conventionally, a graphite member is brought into or removed from the chamber of a crystal pulling apparatus by physical labor performed by a worker(s). However, the above-mentioned tendency toward larger graphite members requires more workers to attend to the handling of the members. Also, a heavier weight and high-temperature heat impose a greater physical burden on workers, and because of graphite being fragile, there is a higher risk of breakage of the members caused by a shock imposed thereon or as a result of their being dropped, while they are being handled.